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United States Patent |
5,558,899
|
Kuzee
,   et al.
|
September 24, 1996
|
Method for the preparation of polysaccharide derivatives
Abstract
A method for the preparation of polysaccharide derivatives comprises
reacting at least a saccharide, such as glucose, maltose or glucose syrup,
a "food grade" polycarboxylic acid, such as citric acid, or inorganic
acid, such as phosphoric acid, which also acts as catalyst, and optionally
a polyol, such as serbitol, under the influence of electromagnetic waves
to give a reaction product at a temperature of 140.degree.-300 .degree. C.
Preferably, the envisaged reaction is carried out in a commercially
available microwave oven having a wave frequency in the range of 900-2500
MHz. The products obtained can be incorporated as low-calorie "bulking
agents" in diet foods, such as dessert, cake and the like.
Inventors:
|
Kuzee; Hendrika C. (Oost Souburg, NL);
Hoeks; Theodorus L. (Bergen Op Zoom, NL);
Visschedijk; Paulus J. (Roosendaal, NL)
|
Assignee:
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Cooperatie Suikerunie U.A. (Roosendaal, NL)
|
Appl. No.:
|
365224 |
Filed:
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December 28, 1994 |
Foreign Application Priority Data
Current U.S. Class: |
426/658; 426/237; 426/241; 426/242; 426/247; 426/804; 536/18.6; 536/126 |
Intern'l Class: |
A23L 001/025 |
Field of Search: |
536/18.5,18.6,126
426/658,237,241,247,804,242
|
References Cited
U.S. Patent Documents
2719179 | Sep., 1955 | Mora et al. | 536/623.
|
3432413 | Mar., 1969 | Vanderhoff | 204/159.
|
3876794 | Apr., 1975 | Rennhard | 426/548.
|
4654039 | Mar., 1987 | Brandt et al. | 604/368.
|
4683297 | Jul., 1987 | Yanami et al. | 536/18.
|
4766207 | Aug., 1988 | Deger et al. | 536/18.
|
4943630 | Jul., 1990 | Jacquinet et al. | 536/123.
|
4996306 | Feb., 1991 | McDaniel et al. | 536/18.
|
5350686 | Sep., 1994 | Jhingan | 435/173.
|
5364794 | Nov., 1994 | Ezure et al. | 536/18.
|
Foreign Patent Documents |
214986 | Oct., 1984 | DE.
| |
1425624 | Feb., 1976 | GB.
| |
Other References
Chen, Shui-Tein et al., "Preparative Scale Organic Synthesis using a
Kitchen Microwave Oven", J. Chem. Soc., Chem. Commun., 1990, pp. 807-809.
|
Primary Examiner: Kepplinger; Esther M.
Assistant Examiner: Tran; Lien
Attorney, Agent or Firm: Young & Thompson
Claims
We claim:
1. Method for the preparation of polysaccharide derivatives comprising
reacting at least a saccharide, an acid, which also acts as catalyst, and
optionally a polyol at elevated temperature and ambient pressure, wherein
the reactants, in the form of a 0.1-90 wt. % water-containing mixture
comprising:
70-99.9 wt. % saccharide
0.1-10 wt. % polycarboxylic acid or inorganic acid
0-20 wt. % polyol
calculated as a dry solids mixture, are heated under the influence of
electromagnetic waves, a reaction product at a temperature of
140.degree.-300.degree. C. being obtained.
2. Method according to claim 1, characterised in that the electromagnetic
waves have a frequency in the range from 3000 kHz to 300 GHz.
3. Method according to claim 1, characterised in that the electromagnetic
waves have a frequency in the radio wave range of about 10-50 MHz.
4. Method according to claim 1, characterised in that the electromagnetic
waves have a frequency in the microwave wave range of about 900-3000 MHz.
5. Method according to claim 1, characterised in that the reactants used
are a dry solids mixture of:
85.5-91.75 wt. % saccharide
0.25-2.5 wt. % polycarboxylic acid
8-12 wt. % polyol.
6. Method according to claim 1, characterised in that the reaction mixture
contains 5-50 wt. % water.
7. Method according to claim 1, characterised in that the saccharide used
is d-glucose, glucose syrups, maltose or maltotriose, the polycarboxylic
acid used is citric acid and the polyol used is sorbitol.
8. Method according to claim 1, characterised in that the water-containing
reaction mixture is heated under the influence of electromagnetic waves
using a ratio of power to the amount of reaction mixture which can be
converted to polysaccharide derivative per unit time of 0.1-6
kW/(kg/hour).
9. Method according to claim 8, characterised in that the water-containing
reaction mixture is heated under the influence of electromagnetic waves
using a ratio of power to the amount of reaction mixture which can be
converted to polysaccharide derivative per unit time of 0.2-1
kW/(kg/hour).
10. Method according to claim 1, characterised in that the method is
carried out continuously.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for the preparation of polysaccharide
derivatives by reacting at least a saccharide, an acid, which also acts as
catalyst, and optionally a polyol at elevated temperature.
2. Description of the Related Art
A method of this type is disclosed in U.S. Pat. No. 3,766,165. More
particularly, in said American patent a method is described for the
preparation of polysaccharide derivatives, in which method d-glucose or
maltose, as saccharide, is reacted in the molten state at a temperature of
140.degree.-295 .degree. C. and under highly reduced pressure in the
presence of a catalytic amount of at most 10 mol % of a "food grade"
polycarboxylic acid, for example citric acid, in the absence of water,
with the proviso that the water produced during melting and polymerisation
is removed immediately. A polyol such as sorbitol can also be used in the
abovementioned reaction.
European Patent 404,227 describes a method which can be carried out
continuously, with which method the desired polysaccharide product can be
obtained both within a short time and without the use of vacuum or the
apparatus required to maintain vacuum conditions. To this end the
reactants, in the form of a mixture of at least a saccharide, a polyol and
a "food grade" polycarboxylic acid are fed through a worm shaft reactor or
extruder operating at elevated temperature and under elevated pressure, a
reaction product at a temperature of 140.degree.-300.degree. C. being
obtained.
Both the method according to U.S. Pat. No. 3,766,165 and the method
according to European Patent 404,227 require the use of a dry pulverulent
reaction mixture as starting material. In European Patent 404,227 it is
also stated that the starting material used in the form of a powder
usually has a particle size of less than 3 mm and preferably of 0.05-1 mm.
SUMMARY OF THE INVENTION
The Applicant has therefore made efforts to develop a method which has a
short reaction time and which can be carried out continuously, with which
method the use of starting materials containing water of crystallisation,
or starting materials dissolved in water, does not constitute an
inhibiting factor for the production of the desired polysaccharide
derivatives to be prepared. The use of a process which is not critical
with regard to the moisture content of the starting materials is very
attractive from an economic standpoint because of the reduction of
starting material costs as a result of the avoidance of costs for working
up the starting materials for the abovementioned methods, such as
comminution, drying etc.
Surprisingly, it has been found that the abovementioned aim can be achieved
if the reactants, in the form of a water-containing mixture of at least a
saccharide, a "food grade" polycarboxylic acid or inorganic acid and,
optionally, a polyol are heated by means of electromagnetic waves, a
reaction product at a temperature of 140.degree.-300.degree. C. being
obtained.
The reaction time required for the reaction according to the invention as
indicated above varies from 0.5-20 minutes, advantageously 1-7 minutes. In
fact, the reaction time is determined by the amount of energy supplied per
kg of reaction mixture.
In terms of properties, the product obtained by the method according to the
invention in principle corresponds to the product obtained in accordance
with the method according to U.S. Pat. No. 3,766,165 and European Patent
404,277, or the product described in U.S. Pat. No. 3,876,794, in
particular with respect to reducing power, pH of a solution of the product
in water, acid number, residual content of saccharide, of polyol and of
polycarboxylic acid, formed levoglucosan and hydroxymethylfurfural (HMF),
non-dialysable fraction, optical rotation and Gardner colour; the
abovementioned patents are incorporated herein as reference.
Using the method according to the invention it is possible, for example, to
heat s water-containing mixture of glucose, sorbitol and citric acid
within a period of a few minutes by means of o electromagnetic waves to a
temperature of about 200.degree. C. with the formation of a product which
has the following characteristics:
glucosecontent.ltoreq.6 wt. %, advantageously.ltoreq.4 wt. %
sorbitolcontent.ltoreq.2.5 wt. %, advantageously.ltoreq.2 wt. %
citric acidcontent.ltoreq.0-75 wt. %, advantageously.ltoreq.0-5 wt. %
levoglucosancontent.ltoreq.4 wt. %, advantageously.ltoreq.2.5 wt. %
solubility in water about 100 wt. % or less, depending on the amount of
polycarboxylic acid used
pH of a 10 % solution in water: about 3
Gardner colour: .ltoreq.10, advantageously.ltoreq.5, in
particular.ltoreq.3.
Suitable saccharides are advantageously glucose, maltose or maltotriose,
glucose syrups and preferably glucose. Glucose can be used for this method
in the form of the anhydrate or the monohydrate.
The polyol to be used in the method according to the invention must be a
product acceptable in the foodstuffs industry or a "food grade" product,
such as, for example, glycerol, erythritol, xylitol, mannitol, galacticol
and preferably sorbitol. The amount of polyol is, for example, 0-20 wt. %,
advantageously 8-12 wt. %, based on the total amount of solids.
The catalyst used is a polycarboxylic acid acceptable in the foodstuffs
industry, or a "food grade" polycarboxylic acid, such as malic acid,
fumaric acid, tartaric acid, the terephthalic acids, succinic acid, adipic
acid, itaconic acid, or the anhydrides of the latter three acids, and
preferably citric acid. Inorganic acids, such as phosphoric acid and
hydrochloric acid are also suitable as catalysts. Said inorganic acids do
not yield "cross-linking", as a result of which the preparation of
polydextrose insoluble in water is not possible using these catalysts.
Depending on the amount of polycarboxylic acid used as catalyst, a product
is obtained which is insoluble, completely soluble or only partially
soluble in water. Roughly it can stated that for the preparation of a
water-soluble product an amount of at least 0.1, for example 0.25-2.5 wt.
% polycarboxylic acid, and for the preparation of a product which is
partially soluble or insoluble in water a larger amount of, for example,
at most about 10 wt. % polycarboxylic acid, based on the total amount of
solids, can be used.
According to the method in accordance with the invention, therefore,
reaction mixtures of:
70-99.9 wt. %, advantageously 85.5-91.75 wt. % saccharide, preferably
d-glucose
0.1-10 wt. %, advantageously 0.25-2.5 wt. % polycarboxylic acid, preferably
citric acid and
0-20 wt. %, advantageously 8-12 wt. % polyol, preferably sorbitol are
advantageously used.
If necessary, water is then added to these reaction mixtures, which are dry
or contain water of crystallisation, so that the water content of the
final starting material has a value of, usually, 0.1-90 wt. %,
advantageously 5-50 wt. %, based on the total starting material.
The method according to the invention can be carried out with the aid of
electromagnetic energy sources generally known from the prior art.
Commercially available microwave ovens are used in the examples; however,
other known electromagnetic energy sources can also be used.
In the method according to the invention, the electromagnetic energy
employed from the sources used is converted into kinetic energy, which
results in a rapid rise in the temperature of the reaction mixture. The
envisaged condensation reaction proceeds better in the presence of water,
which is highly surprising in view of the fact that, according to the
prior art, such as U.S. Pat. No. 3,766,165, the water content had to be
restricted to an absolute minimum during the envisaged reaction. Within a
relatively short reaction time of, for example, 0.5-20 minutes,
advantageously 2-7 minutes, an end product can be obtained which has
characteristics which are equivalent to the characteristics of the
products which are obtained in accordance with the methods according to
the above-mentioned literature, i.e. U.S. Pat. Nos. 3,766,165 and
3,876,794 and European Patent 404,277.
The reaction mixture is put inside the electromagnetic wave oven and
exposed to electromagnetic radiation to allow the condensation reaction to
proceed. The reaction may be carried out batchwise by introducing the
reaction mixture in reaction vessels. The reaction may also be carried out
continuously by feeding the reaction mixture as a layer or in small
containers on a conveyor belt through the electromagnetic wave oven. The
reaction mixture can be transported through the electromagnetic wave oven
at a speed such that a residence time of 0.5-20 minutes, advantageously
2-7 minutes, is obtained.
The frequency range of the electromagnetic waves for the preparation of
polysaccharide derivatives can vary from 3000 kHz to 300 GHz. The
frequencies most used industrially are in the radio wave range of about
10-50 MHz and in the microwave range of about 900-3000 MHz. All of the
industrial frequency ranges indicated here are suitable for the
preparation of polysaccharide derivatives according to the invention.
The power of the electromagnetic energy sources can vary between 0.60 and
100 kW. In fact, the reaction time is determined by the amount of energy
per kg reaction mixture. The ratio of power to the amount of reaction
mixture which can be converted into polysaccharide derivative per unit
time is usually 0.1-6 kW/(kg/hour), advantageously 0.2-1 kW/(kg/hour).
Advantages of the present method compared with the methods disclosed in
U.S. Pat. No. 3,766,165 and European Patent 404,227 are, inter alia, that
the method according to the invention:
preferably proceeds in the presence of water, so that it is not necessary
to use a starting material which both has to be dry and has to have a
particle size of less than 3 mm;
can be carried out using non-viscous or viscous solutions of starting
materials (syrups), as a result of which an appreciable saving in costs in
respect of starting materials can be achieved;
is very "simple" to carry out from the technological standpoint, since
neither vacuum nor high pressure has to be employed;
can be carried out continuously;
requires only a very short reaction time; and
with the method according to the invention undesired side reactions are
more easily controllable, which, for example, is reflected in a lower
Gardner colour.
The products obtained in accordance with the method according to the
invention can be added, in the non-neutralised or neutralised form, as
low-calorie "bulking agents" to diet foods and the like in order to impart
to said foods desired characteristics such as texture and the like, which
usually are obtained from high-calorie products such as sugar and/or fat.
Examples of such foods ape desserts, cakes, biscuits, chewing gum, sweets,
dressings, salads, ice cream mixtures and hard and soft candy.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The invention is explained in more detail with the aid of the following
examples; however, these examples must not be regarded as implying any
restriction.
EXAMPLE I
A mixture of 81.56 wt. % glucose monohydrate, 8.3 wt. % sorbitol, 0.64 wt.
% citric acid monohydrate and 9.5 wt. % water was mixed homogeneously. 25
g of this mixture was transferred to a 600 ml glass beaker. This glass
beaker was then placed in a Philips Cooktronic M716 microwave oven which
had a frequency of 2450 MHz and s maximum power of 700 W. After heating
for 3 minutes at the maximum setting, a pale yellow product at a
temperature of 199.degree. C. was obtained. This product had s Gardner
colour of 2.5 (10 wt. % solution in water) and the following composition:
Glucose: 1.75 wt. %;
Sorbibol: 1.35 wt. %;
Citric acid: 0.25 wt. %;
Levoglucosan: 2.00 wt. %; and
polydextrose making up the remainder.
The pH of a 15 % solution was 2.85. The viscosity of a 70 % w/w solution in
water was 2355 cps. The product obtained was completely soluble in water.
EXAMPLE II
(comparison example)
A mixture of 89.15 wt. % glucose anhydrate, 10 wt. % sorbitol and 0.85 wt.
% citric acid monohydrate was mixed homogeneously. 25 g of this
pulverulent mixture was transferred to a 600 ml glass beaker. This glass
beaker was then placed in a Philips Cooktronic M716 microwave oven which
had a frequency of 2450 MHz and a maximum power of 700 W. After heating
for 8 minutes at the maximum setting, only a fraction of the material had
reacted. The reacted yellow product, which had a Gardner colour of 4.5 (10
wt. % solution in water), had the following composition:
Glucose: 2.40 wt. %;
Sorbitol: 1.35 wt. %;
Citric acid: 0.35 wt. %;
Levoglucosan: 2.25 wt. %; and
polydextrose making up the remainder.
The temperature of the reacted material was 195.degree. C. The rest of the
reaction mixture had not reacted and the temperature of this fraction of
the material was 30.degree. C. As a result the total reaction product had
a Gardner colour of 2 (10 wt. % solution) and the following composition:
Glucose: 46.0 wt. %;
Sorbitol: 5.7 wt. %;
Citric acid: 0.65 wt. %;
Levoglucosan: 1.10 wt. %; and
polydextrose making up the remainder.
The product obtained was completely soluble in water.
EXAMPLE III
After homogenising 70.82 g glucose anhydrate, 7.87 g sorbitol, 5.57 ml
H.sub.3 PO.sub.4 (0.148M) and 15.74 g water, the mixture was transferred
to a 1000 ml glass beaker. This glass beaker was placed in a Philips
Cooktronic M716 microwave oven which had a frequency of 2450 MHz and a
maximum power of 700 W. After heating for 4 minutes at the maximum
setting, the product temperature was 203.degree. C. and the product, which
was completely soluble in water, had the following composition:
Glucose: 3.15 wt. %;
Sorbitol: 1.40 wt. %;
Levoglucosan: 1.60 wt. %; and
polyglucose making up the remainder.
The pH of a 15 % solution in water was 2.91.
EXAMPLE IV
A mixture of 90 wt. % glucose anhydrate, 1.0 wt. % citric acid and 9 wt. %
water was homogenised. 50.0 g of this mixture was transferred to a
microwave oven which had a frequency of 915 MHz and a maximum power of 650
W. After heating for 5 minutes at the maximum setting, a dark yellow
product at a temperature of 204.degree. C. was obtained, which had a
Gardner colour of 4 (10 wt. % solution in water) and the following
composition:
Glucose: 2.05 wt. %;
Citric acid: 0.45 wt. %;
Levoglucosan: 1.80 wt. %;
HMF: 580 ppm; and
polyglucose making up the remainder.
The viscosity of a 70 % w/w solution in water was 2800 cps. The product
obtained was completely soluble in water.
EXAMPLE V
0.6 g citric acid and 6.6 g sorbitol were added to 100.0 g glucose syrup
which had a DP (degree of polymerisation) of 4 and a solids content of 75
wt. %. 50.0 E of this mixture was placed in a microwave oven which had a
frequency of 2540 MHz and a maximum power of 700 W. After heating for 3.5
minutes at the maximum setting, a pale yellow product at a temperature of
200.degree. C. was obtained, which at 420 nm had an absorption of 0.213
(10 wt. % solution in water) and had the following composition:
Glucose: 1.95 wt. %;
Sorbitol: 1.55 wt. %;
Citric acid: 0.30 wt. %;
Levoglucosan: 1.50 wt. %;
HMF: 375 ppm; and
polydextrose making up the remainder.
The product obtained was completely soluble in water.
EXAMPLE VI
30.0 g of a solution which contained 8.92 wt. % glucose, 1.00 wt. %
sorbitol, 0.08 wt. % citric acid and 90.00 wt. % water was transferred to
a 400 ml glass beaker. This beaker was then placed in a microwave oven
which had a frequency of 2450 MHz and a maximum power of 700 W. After
heating for 9 minutes at the maximum setting, a yellow product at a
temperature of 205.degree. C. was obtained, which had the following
composition:
Glucose: 6.05 wt. %;
Sorbitol: 2.00 wt. %;
Citric acid: 0.35 wt. %;
Levoglucosan: 2.15 wt. %; and
polydextrose making up the remainder.
The product obtained was completely soluble in water.
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